1. Field of the Invention
This invention relates to a furnace and method for decomposing solid waste materials, such as automobile tires, and using the exhaust as a source of heat which is supplied to a selected area.
2. Description of the Prior Art
Due to today's environmental concerns, the disposal of solid waste has been a particular problem. Much of this solid waste consists of synthetic materials, such as rubbers or plastics, which do not readily decompose or biodegrade. The continued production of these synthetic materials in order to support the world's ever increasing population makes it even more important that solutions be developed for disposing of these waste materials. The available space in land fills is limited and recycling measures have had little, if any, significant impact on reducing the amounts of solid wastes that are produced and which continue to accumulate.
One alternative is to incinerate or burn these materials in high temperature furnaces. Care must be taken, however, in order to ensure that complete combustion of the solid wastes occurs before exhaust gases are vented to the atmosphere. Incomplete combustion can result in the formation of poisonous carbon monoxide and other pollutants.
One particular area which would benefit from the combustion of these solid waste and which would supply high enough temperatures to ensure complete combustion is in combination with high temperature rotary kilns, such as rotary lime kilns. Lime kilns typically require high temperatures, above 1400.degree. F., in order to effectively calcine lime. Because of the high temperatures present in these rotary kilns, solid waste and other waste materials have sometimes been added or introduced directly into the lime kiln where they are decomposed or combusted into harmless combustion products, mainly water and carbon dioxide. These products are then safely vented to the atmosphere. One of the problems with this method of decomposing of waste materials is that incombustible matter found within the solid waste remains in the rotary kiln and can contaminate the lime or other materials being processed therein.
Because of the potential contamination of process materials within these rotary kilns, it is often desirable to combust the waste material separately from the rotary kiln or convert the waste materials into a useable fuel free of incombustible matter that can contaminate the materials within the rotary kiln. This can be done by means of completely combusting these materials and using the combustion products as a supplemental heat source which is then introduced into the rotary kiln, or by decomposing the waste materials into combustible gases. The later is often referred to as pyrolysis. Pyrolysis occurs when the solid waste are heated to temperatures wherein components of the waste material are volatized or gasified. The pyrolysis products are then introduced into to the rotary kiln where they are burned. These pyrolysis products usually consist of carbon monoxide and light hydrocarbons.
There have been a variety of furnaces designed for the decomposition or combustion of solid waste, particularly waste tires. There is a need for improvements however. One limitation of these prior art furnaces is their inability to operate continuously while removing undecomposed waste material, such as steel or other metals, from the furnace. Many of the continuously operating furnaces require a fluidized bed formed from a fluid-like refractory material, such as sand. Because the waste material is usually dispersed throughout the fluidized bed, it is necessary to remove the refractory material of the fluidized bed along with the undecomposed material. The undecomposed material is then separated out from the refractory materials before the refractory materials are returned to the furnace.
What is needed is a furnace for decomposing solid waste materials, such as automobile tires, which can be operated continuously and which provides a means for separating and removing noncombustible or undecomposed material from the furnace without interfering with the continuous operation of the furnace and which does not utilize a fluidized bed of refractory material that must be replaced within the furnace as the noncombustible or undecomposed materials are removed.